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How We Assess Your Precious Embryos - Part 2

Here's a link to part 1 if you missed it!



A ‘blastocyst’ is what we call an embryo that is 4-6 days old and has changed to form a more complex structure that is filled with fluid. It is the final stage an embryo must achieve before it will have a chance to try to implant into the lining of your womb.

However, not all embryos can go through this change but those that do automatically have a higher potential for achieving pregnancy. This is why we wait until this stage before transfer/freezing when there are a number of embryos we are looking at, to rule out those that remain stuck at the previous stage.

If you are lucky enough to have a choice of more than 1 good looking blastocyst, then we can go back over the days’ assessments and see how each of those embryos grew and how it had looked to make our final choice of the very best one. 

The bottom line is, some embryos in a group will always have more potential than others. Some will grow better, or look better grades than others. The embryologist’s job is to use all of the embryo assessments we make over the days to identify these better embryos so that we can select them for your transfer and/or freezing. 

For some, only a single embryo is available; in which case we know that one is the best one you have, so we’ll make some early assessments to make sure it started to grow and divide and then it will be able to be transferred (or frozen) from day 2-3. For others, multiple embryos are available so we need to make our assessments for longer to be sure we are identifying the better ones. 

This is why some of you at CARE Nottingham will have earlier, day 2/3 embryo transfers and others will wait until day 4 onwards. 


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